1. Field of the Invention
The present invention relates to a tool replacement method for machine tools and a nut driver therefor, and in particular to tool replacement method and a nut driver for a machine tool including a spindle having a chuck provided on a distal end thereof for chucking a tool and a nut screwed to the distal end and rotatable for tightening and loosening the chucking.
2. Description of Relevant Art
In a conventional machine tool, the spindle has a chuck adaptive for chucking thereto one of a variety of rotary tools to be replaceabIe with another. For example, the collet chuck falls in a variety of types, such as a draw-bar type configured to draw in or push out a chuck by a draw bar axially movable in the spindle, or a screw-mount type configured with a nut screwed on a distal end of the spindle and configured to be tightened or loosened to thereby tighten or loosen a chuck.
The draw-bar type is configured for reciprocating the draw bar, e.g. by a cylinder, to tighten or loosen the chuck, and easily adaptive for automatic replacement of tool.
However, the screw-mount type employs a rotating tool such as a wrench for manual replacement of tool.